ABC News's Brian Ross delivers the latest news on the tragedy in Orlando. A horrible crime of terror and act of hate took place there over the weekend in which over 50 people will killed by a gun man at a night club that was a refuge and place of safety for the LGBT community in Orlando. It is the worst mass shooting in U.S. history. The gunman Omar Mateen was known for his short temper and violent behavior as explained by his ex-wife. He also did not like to be around people that are gay. It is reported that he made several calls to 911 during the massacre and pledged allegiance to ISIS.